A. Field of the Invention
The present invention relates to electrical junction boxes which are known as pull boxes and used to enclose interconnections between electrical power mains cables and electrical power distribution cables connected to devices such as municipal and highway street lighting fixtures, traffic signals and the like. More particularly, the invention relates to a novel theft-dissuading security lid for wall-mounted wire pull boxes, and novel tools and methods for retrofitting existing wall-mounted pull boxes with the security lid.
B. Description of Background Art
Electrical junction boxes are widely used to connect electrical power input cables of street lights installed along streets and highways to electrical power mains. Such junction boxes, for reasons which will become apparent from the following discussion, are typically referred to as pull boxes. A first, ground-mounted type of pull box is typically installed in a shallow pit dug into the ground, and has generally the form of a rectangular ring-shaped concrete shell. The open bottom of the shell is fitted down into a pit which has been dug into the ground and has two or more conduits that protrude upwardly from the bottom of the pit. The conduits have protruding outwardly from open upper ends thereof insulated electrical power line cables which are strung through the bores of the conduits, and include a power source conduit that contains cables which are connected at distal ends thereof to a power pole or other source of electrical power, and pulled through the conduit, which is horizontally disposed under the ground. The pull box pit also has a second conduit which is disposed between the pit and a destination requiring electrical power, such as a street light or highway lighting fixture.
A second, wall-mounted type of pull box in common use consists essentially of an open-top, rectangular metal box which is inserted into a similarly shaped cavity or recess formed in a concrete highway or street barrier or sound wall.
Within the hollow interior space of a pull box shell, electrical interconnections or splices are made between copper wires of power mains cables and power distribution cables leading to a lighting fixture or other electrical power consuming device. Usually, the interconnections include high-current fuses. After interconnecting splices have been made between power mains cables and power distribution cables which extend out through the exit conduit to a street light or other electrical device, a cover lid is installed on the pull box.
The cover lid of a ground-mounted pull box typically consists of a concrete slab which is lowered into a recess in the upper end of the concrete shell of the pull box, and easily lifted off from the shell by inserting a screwdriver or pry bar into a slot in the lid. The cover lid of a wall-mounted pull box typically consists of a flat metal plate which is bolted to a pair of laterally opposed mounting flanges which extend from the upper edges of opposite vertical side panels of the pull box.
Pull boxes of the type described above are used extensively for such applications as providing electrical power to a row of light standards used to illuminate a street or highway. In such applications, electrical power from a power line main located near one of the light standards is supplied to a first light standard through electrical interconnections made between power cables entering the pull box through a first, power mains source conduit and supply cables to the light standard exiting the pull box through a second, feeder conduit disposed between the pull box and the first light standard.
In a typical power distribution arrangement for a row of street or highway light standards, a first pull box which provides power to a first light standard in a row or chain, also has protruding into the interior space at the end of a third conduit which contains electrical wires that are disposed through the third conduit which runs under the surface of the ground to a second pull box located near a second light standard in a row of light standards.
Electrical connections are also made in the first pull box between the power mains cables and the cables leading to the second pull box, thus providing electrical power from the mains to the second light fixture.
In this way, electrical power from a single power mains source is provided to a row of street lighting fixtures in a series of pull boxes containing interconnected electrical wires in an arrangement sometimes referred to as a “daisy chain.”
Although the daisy chain power distribution arrangement of pull boxes described above is straight forward and efficient, problems have recently arisen when the arrangement is implemented with existing pull boxes, for the following reasons.
In recent years, the price of copper has risen sharply, from a cost of one dollar U.S. per pound in December 2008 to four dollars and fifty cents U.S. per pound in 2011. Because of the steep rise in the price of copper as a commodity, thieves have been motivated to engage in theft of copper wire which is then sold to scrap dealers.
One technique for stealing copper wire which has gained in popularity with thieves involves removing the lid of a pull box in a daisy-chain of pull boxes, removing the lid from an adjacent pull box in a daisy chain, freeing the ends of the wires in both pull boxes by cutting the wires, and pulling the freed lengths of wires out of one or the other of the pull boxes. There have been several well documented cases in the United States where thieves who made the initial cuts in daisy-chain power cables, apparently oblivious to the fact that cables carried electrical power, were incinerated for their efforts.
In response to problems including dangers to the public resulting from the loss of street or highway lighting because of theft of copper wire used to supply power to the lights, the present inventors disclosed in co-pending patent application Ser. No. 11/933,996 for Wire Theft Protection For Pull Boxes a security enclosure for ground-mounted pull boxes. The security enclosure disclosed in that application has various security measures which thwart access to wire cables contained within the enclosure, and has proved to be substantially effective in reducing theft of wire from pull boxes fitted with the security enclosures. The present invention was made in response to a need for a wire theft protection apparatus useable to protect against theft of copper wire from wall-mounted pull boxes.